City picked up the final Kerikeri wicket off the penultimate ball with a run out courtesy of Smith and Witten to end their innings at 141 all out.
City's reply started off on shaky ground when a good ball snuck through Ashton Pattenden's defence to have him for a third-ball duck.
Witten (45) and Lang (35) got their chase back on track, combining for an 89-run partnership for the second wicket which proved to be pivotal in the contest.
Renara (2 for 25) removed both of the batsman but Harry Sekhon (22) and Smith (19 not out) saw City home with just under 15 overs to spare to get their 40-over campaign off and running.
Maungakaramea meanwhile had a tough time putting away a determined Kamo High School at Kensington Park.
Batting first, Kamo High showed a lot of grit and determination as runs weren't easy to come by against a side with two players with the same name.
Nathan Parkes (53) led the way for the high schoolers as he and Max Turner (47) staved off some tight bowling from Maungakaramea to forge a 96-run partnership.
Kamo High's Roger Turner said the pair were highly impressive on a day where a couple of dropped catches proved costly.
"They're only Year 9 and 10 boys those two so we were incredibly happy with their efforts," he said.
"A couple of dropped catches from us changed the game unfortunately."
Gurjent Singh, the bowler, was the pick of the Maungakaramea attack, taking three for 29 off his eight overs, helping his side restrict Kamo High to 158 for 4 in their 40 overs.
Billy Alexander-Crawford (2 for 17) was the leading wicket taker for Kamo High as they made Maungakaramea really work in their pursuit.
Gurjent Singh, the batsman, in the Maungakaramea team top scored with 76.
However, the dropped catches meant Kamo High couldn't quite stop their opposition reaching the target with two wickets in hand.